Genetic engineering refers to the scientific process of manipulating genetic material. It involves altering, replacing or transferring genes from one organism to another for some specific purpose. Usually, genes are transferred to impart some characteristic of the source organism to the target organism.
Genes are the primary units of heredity. Gene factors, also known as traits, are transferred from one generation to another. Genes are DNA or RNA segments, are found in fixed positions in the chromosomes and contain protein-making instructions. The cell reads these instructions, and then knows which proteins to produce to carry out the cell’s functions. Genes control enzyme production. Variations of genes are called alleles.
Proteins are organic macromolecules and are made up of one or more linear chains of 200 to 300 amino acids linked by peptide bonds. The gene arrangement sequence determines the order of amino acids.
Chromosomes are present in all animals and plants. Found in rod-shaped pairs inside the cell nucleus, each chromosome contains a single long DNA molecule. This DNA molecule contains gene segments. Most cells in an organism’s body carry the same set of chromosomes in their nuclei.
DNA is the abbreviation of deoxyribonucleic acid. DNA has a double-helix polymer structure; two DNA strands wind around each other in a spiral form. DNA is made of thousands of nucleotides or polynucleotides, which are chemical compounds of a nucleic acid and are made up of a five carbon sugar called deoxyribose, a phosphate and a nitrogen base. There are four types of nitrogen bases – adenine, thymine, guanine and cytosine. As there are four different nitrogen bases, there are four types of DNA nucleotides. The order of the nitrogen bases in DNA strands determines the genetic code. With some variations, most species have the same DNA genetic code. In genetic engineering, gene splicing methods are used to alter DNA.
Gene splicing involves taking a gene from the DNA of one organism and splicing or attaching it with an enzyme called ligase to another DNA molecule from either the same organism or another organism.
RNA is the abbreviation of ribonucleic acid. It is built like DNA, except it is single stranded and contains the nucleotide uracil instead of thymine and ribose instead of deoxyribose. Messenger RNA (mRNA) carries the DNA information needed for the production of proteins. Transfer RNA (tRNA) recognizes nucleotide triplets (codons) on the mRNA and carries the corresponding amino acid to the site of protein synthesis.
Enzymes are proteins developed by the body to act as catalysts. They speed up or increase chemical reactions in the body by building up or breaking down molecules, but are not themselves affected or changed. Enzymes are necessary aids in the digestion process. There are many different types of enzymes, grouped according to function in six groups - hydrolases, lyases, transferases, isomerases, oxidoreductases and ligases.